Soy Is On Top As A High-Quality Plant Protein

December 6, 2011

Evaluation method supports soy protein as a high-quality protein similar to meat, eggs and dairy

The importance of protein in the human body is undeniable. However, the idea of what makes a protein a “quality protein” has not been as easy to determine. A new study from the Journal of Agriculture and Food Chemistry takes a closer look at the criteria for determining the quality of a protein.

Traditional methods for determining protein quality have shown animal proteins such as milk and eggs to be high in quality. However, those who are interested in a plant-based diet, or diversifying their proteins, have a more difficult time determining which of their choices are high in quality. Testing methods have shown most plant proteins, such as pea protein, are lower in quality than animal-based proteins.

“Accurate methods for determining protein quality are key to helping people plan a healthful diet,” said Glenna Hughes, MS, research scientist at Solae. “Due to the increasing interest in including plant-based proteins in the diet, accurate information on protein quality is needed in scientific literature to help educate consumers and healthcare professionals on this topic.”

The Food and Agriculture Organization (FAO) and the World Health Organization (WHO) recommend using the protein digestibility-corrected amino acid score (PDCAAS) as a simple and scientific procedure for assessing protein quality. The PDCAAS methodology focuses on three different parameters: the amount of each essential amino acid the protein contains, how easily the protein can be digested, and by taking both of those parameters into account, whether the protein meets the FAO/WHO’s amino acid requirements set for children aged two to five years, as they have higher needs to support growth and development than adults.

According to this study, soy protein has a PDCAAS of 1.00, meaning it is a high-quality protein that meets the needs of both children and adults. Eggs, dairy and meat proteins also have a PDCAAS score of 1.0.

However, soy protein is the only widely available high-quality plant-based protein that achieves this score.

“It’s important for people to understand that a plant-based diet is healthy, but that not all proteins are created equal,” said Connie Diekman, RD, LD, FADA. “If you are planning a vegetarian diet or want to incorporate plant-based proteins in your diet, understanding protein quality using the PDCAAS scale can allow you to select proteins that score higher, such as soy, to ensure that you are getting the essential amino acids you need.”